Figure 4From: Digital anatomical measurements of safe screw placement at superior border of the arcuate line for acetabular fracturesTo section 2 and 3, the line tangent to the expanded arc through the screw entrance point was recorded as the length of the screw, d 1 . The angle between the tangent line and the normal plane was recorded as α. The angle between the line connecting the screw entrance point and the intersection point and the normal plane was recorded as β.Back to article page